Applications have also been filed directed to an Economical Lifting Devicexe2x80x94Trunk Jack, and Economical Lifting Devicexe2x80x94Power Unit For Use With A Jack Stand and Lift Bridge, as described in the present specification.
The invention relates to a low cost consumer device for lifting and supporting an object i.e. a corner of an automobile; particularly to a low cost consumer jack, and also to a low cost two part jacking system including a power unit that can be used to place and elevate a jack stand. The inventor of the present invention is a pioneer of the two part jacking system holding numerous issued and pending patents for a two part jacking system and related products and processes as described below. All such prior art patents and applications are incorporated herein by reference.
Briefly, the commercial two part jacking system consists of a power unit and a set of separate mechanical jack stands. Examples of the two part jacking system and mobile power unit are described in detail in U.S. Pat. Nos. Re.32,715 and 4,589,630. Some examples of the jack stands are described in detail in U.S. Pat. Nos. 4,553,772; 4,490,264; 5,110,089; 5,183,235 and 5,379,974. The stands are capable of being vertically extended and retracted from the garage floor or road surface and, when extended, can be locked in place at any desired position by a ratchet and pawl assembly. The commercial power unit has a mobile chassis adapted to carry a plurality of the jack stands, and has a pair of lift arms adapted to mate with the outermost jack stand for placement and removal.
In use, the commercial mobile power unit is operated entirely from its handle. It is maneuvered under a vehicle to place a jack stand in a desired location for lift and supporting the vehicle. The power unit is activated from the handle, and this jack stand is then vertically extended to the desired height, thus lift the vehicle on the stand. By operating the controls at the end of the handle, the operator can cause the power unit to disengage from the stand, and the stand will remain locked in its extended supporting position under the vehicle. After the stand is raised and locked in place to support the vehicle or other load in a lifted position, the power unit lift arms are lowered and the power unit is disengaged from the stand and pulled away, leaving the stand in position supporting the load. Another jack stand, carried within the chassis, is automatically transferred to the forward end the chassis for placement at another desired location of the vehicle or for use to lift and support another vehicle.
To lower the vehicle and remove the stand, the power unit is maneuvered to reengage with the stand. The engagement causes any existing jack stands carried within the chassis to be automatically transferred rearward within the chassis. By manually operating a control at the end of the handle, the operator can cause the power unit to reengage with the stand, and to disengage the ratchet locking mechanism of the stand and lower the stand to its original position. The power unit remains engaged with the stand and can be pulled away from the vehicle with the stand carried within the chassis.
The original commercial power units were adapted to carry up to four jack stands within the chassis. Additional jack stands could be purchased and arranged at various stations on the garage floor to reload the power unit, so that a single power unit could be utilized to efficiently place and actuate numerous jack stands. It was found that many commercial users would utilize all of their available jack stands, and the power unit was thereafter useless until another jack stand was available to be extracted and reused. The present inventor developed a slide forward bridge that adapted the power unit to function as a load-lifting jack to more fully utilize the power unit. Co-pending patent applications have been filed on the features of the power unit convertible into a load-lifting device.
Most of the prior art lifting devices, including those of the present inventor, are very rugged xe2x80x9ccommercial qualityxe2x80x9d products involving many castings and machined parts that require welding for fabrication and assembly. It would be highly desirable to design and develop the innovative jack systems in a low cost xe2x80x9cconsumer qualityxe2x80x9d configuration that involved minimal welding and machining during fabrication and assembly.
In view of the foregoing problems and desirable features of a two part lift and supporting system, it is an object of the present invention to provide a consumer jack and a consumer power unit for use with a consumer jack stand, that can be economically fabricated from sheet metal and steel plate with little or no machining, and can be assembled with little or no welding.
The foregoing objects are accomplished by an economical jack stand for use with a power unit. The jack stand includes a rectangular base plate with a tubular housing having an upper end and a lower end, with the lower end attached to the base plate and extending vertically therefrom. The housing has a forward side, a rearward side, a left and right side.
The jack stand has a xe2x80x9cUxe2x80x9d shaped ratchet shaft having an upper end and a lower end, with ratchet teeth on the forward edges thereof, telescopically inserted within the housing and extendable and retractable within the housing. The shaft has a lift collar mounted on the upper end for engagement with the power unit.
The housing has a pair of pawls interconnected by a D-pin, with each pawl adapted to be engagable with a respective tooth of the ratchet shaft. The pin is pivotally attached to flanges at the upper end of the housing. The pin is rotated by an actuating spring that has an upper end attached to the D-pin, and has a generally vertical handle portion, and has a generally horizontal lower portion including a first position indention and a second position indention.
The housing includes a slotted opening adapted to receive the lower portion of the actuator spring whereby the first position indention is engagable with the slotted opening to position the pawls into engagement with the teeth of the ratchet shaft. The second position indention is engagable with the slotted opening to position the pawls into disengagement from the teeth of said ratchet shaft.
The major components of the jack stand are suitably formed from standard sheet metal and metal plate stock with minimal machining and welding required to form or assemble the components. The base plate is suitably stamped from steel plate. The housing is defined by a piece of sheet metal having a flat pattern including the rearward side with the respective sides and flanges all extending outward from the rearward side. The housing can be formed from a single piece of sheet metal that is stamped to form the apertures and the periphery defined by the flat pattern; the flat pattern is further formed by progressive folds of the stamped flat pattern into the sides of the housing without the need for welding. The ratchet shaft can similarly be formed from a flat pattern that is readily stamped and folded into the desired configurations without the need for machining and welding.